Theory2, some believe that the monolithic circle was constructed by aliens who came to Earth along time long ago i on the other hand think its to far out and unbeleivable. the theorys were that it was a alien landing pad that the aliens had used to come and land on earth, they also thought that it was an intergalactic gift sent here from space along time ago. the theory is supported by people who beleive in studies of intergalactic life or alien enthusiasts. crop cirles alo occur quite frequently were stonehenge is that is also what helps the theory become more possible also magnetics lines, were the parts of the earth meets wich are also around stonehendge are thought to be extraterrestrial markings.